This is how the pen is on your jacket.
Open the loop until you reach the picture above.
Pull the loop back over the fabric of your jacket.
Slide the pen back out of the buttonhole.
The pen is now free again.
To put the pen on someone else, all you have to do is reverse the steps. If in the end you cannot take it back off, scissors are your last option :)
I hope you had fun with the magic-pen. Use it at the next party or business meeting and enjoy the reactions. If you are looking for a highlight for your event, please contact me!